Electrical contact



Jan. 14, 1930. A. T. CAR TER ELECTRICAL CONTACT Filed Nov. 6. 1922 B Inveritor momey Patented Jan. 14, 1930 UNITED STATES PATENT OFFICE AINSLIE T.-CARTER, F ALBANY, NEW YORK, AS SIGNOR, BY MESNE ASSIGNMENTS, TO GENERAL RAILWAY SIGNAL COMPANY, A CORPORATIONOF' NEW YORK ELECTRICAL CONTACT Application filed November My invention relates'to electric contacts and particularly to contacts used in relay and other devices for controlling the opening and closing of electrical circuits. I will describe one form of electric contacts embodying my invention, and will then'point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a view partly in side elevation and partlyin verticalsectionof two electric contacts embodying my invention with which a controller arm alternately engages. .Fig. 2 is a sectional view on the line 2-2 of Fig. 1.

Similar reference characters refer to simiv, .lar parts in each of the views.

. In the drawings I have illustratedmy invention as being applied to a relay device, such as is commonly used for controlling the operation of railway signaling devices. The

. relay is shown as comprising a. top plate 1 of insulating material such as porcelain and serving as asupport, abottom plate 30, and glass side walls 81, separated from the top and terminate in pole pieces. 3, 3, resting against the underside of the top plate. The electromagnet A controls an armature 5 constituting a controller arm which is pivotally mounted at 6 in any desired manner. The controller arm 5 engages afront contact 8 to control one circuit and a back contact 9 to control another circuit. In the drawings I have shown only one front and one back contact and one finger or arm F, but in accordance with the usual practice, and especially in relay practice there will be a number of such contacts and controller arms each behind the other as viewed in Fig.1.

The contact member 8 in the form here -shown,'isof carbonand conical in shape, and

and bottom platesby gaskets '33. The top I and bottom plates are spaced by the side walls which cores project through the top plate 1.

e, 1922. Serial No. 599,187.

is supported in a tubular shell 8 of electroconductive material, the inner surface of which is likewise conical in formation. In assembling these parts the carbon member or button is pushed into the shell so that any strain whichis put into the carbon button is distributed over the whole conical surface of this member. Thecarbon button is held in position in the shell 8" by placing on top of this button a cylindrical block 8 which fits the shell snugly,-this block being pressed in until it rests on the carbon button and so holds the latter firmly in position in the shell. The assembly is finished by spinning or pressing the upper rim of the shell 8 over the bloc k.8. The block 8' is provided with a threaded hole to receive a threaded terminal post 8 by means of which thecontact is supported, (in this instance the top plate 1). whereby the vertical position of the carbon button 8 may be adjusted by turning the shell8 on the post. This shellis locked in adjusted position by means of a nut 19 on the post 8. v

, The back contact 9 comprises a contact plate'9 preferably of silver or other suitable material, attached to a contact spring 15. This spring 15 is made of high grade noncorroding spring material such as phosphor bronze, and is riveted at 16 to a comparatively rigid arm17. The outer or free end of the spring 15 is bent downwardly and provided with a slot a which receives, with considerable clearance, the adjacent end of the arm 17, as best shown in Fig. 2. The end of the spring 15 normally tends to engage the under surface of the arm 17 that is to say, the normal bias of the spring is such as to cause the spring to move away from the arm 17 as far as permitted by the vertical limits of slot a. In other words, spring. 15 is assembled with. an initial trapped upward pressure. When the magnet is de-energized so that the contact finger F engages the plate 9 the spring15 will be depressed untilthe weight of the armature and the parts carried thereby is balanced. Then when the magnet becomes energized the spring 15 will follow the movement of the armature and of contact tip 9 to an extent limited by the slot a. It will be seen, therefore that the back contact spring with a locknut 18 and passes through the smooth bored end of bracket l l and the threaded bored lower end of the arm 17, to engage the upper portion of this. arm whereby the exact desired position of the contact spring 15 may be secured during adjustment and calibration of the relay by adjusting the screw 18 and thus raising or lowering, as a unit, the spring 15 and upper leg of arm 17 The structure described hereinbefore for mounting the carbon button 8 has several inn portant advantages among which are the following: A comparatively large contact area exists between the carbon button Sand the shell 8. The lower surface of the contact button i. e.' the surface which is presented to the tip 12, is rounded or spherical in formation so that slight inaccuracies in the alignment of the tip 12 will not aiiect the contact between. this tip and the button 8. The vertical adjustment of the button 8 can be carried out to a very fine degree of accuracy by screwing thismember up and down on the terminal post 8 to any'ira'otion of a turn.

' The shell 8 is kept in tension, thus maintaining pressure between thisshell and the carbon button, and so maintaining a good contact between the two. 7 I r ,7 The constructionflof the back contact 9 overcomes certain d-iihcultieswhich have heretofore been encountered in back contact construction, and provides for adjustment as hereinhefore explained. Onefeature of this contact is that the spring member 15 is of generous size, so that it can be easily handled without damage, and of such shape that its spring'pressure is not subjectto change due to changes in internal stresses of the material which may be caused by bending during fabrication. It will be noted that, this spring member 15 has but one bend, which bend is 90, so that, even if the stresses at this bend should change, the bent portion, that is, the vertical portion will change its relative position but very slightly. It will be noted that thevertical portion hasa rectangular hole a which receives'the end of the arm 17, the purpose of this construction isto; obtain a back contact which is restrained in both its up and down movement. By virtue of this design it is possible to trap an initial pressure in thespring 15 without putting a permanent bend in the horizontal portion of the spring, this being done by merely over-bending or under-bending the arm 17 as may be desired;

in other words, a slight bend is put into spring 15, which bend, however, does not causea permanent set in the spring material as the stresses in this member may easily be kept below the elastic limit. The contact plate on this spring is a silver rivet which can easily be inserted in a small hole punched in the spring, so that no soldering operation at this point is required, and, consequently,

there is no danger of drawing the temper of means of the screw 18 and the shape of the arm 17 the contact is adjustable without changing the pressure trapped in the spring 1 5; in other words, after'assembling the:contact'in the relay the position of the contact plate 9 may be adjusted either up or down without changing the pressure originally trapped in thespring 15, thus providing a feature, which, as will be well-understood, is highly desirable. 7

lVh'a-t I claim as my invention is: 1 1. A contact structure comprising a mov able member pivoted at one end and provided with a contact element at the other end, a flexible contact spring coacting with said member and biased to move toward said 'member, and means forilimiting the movein one direction, a relatively rigid supporting arm for said, spring having a portion thereof passing through an opening n said spring and limiting the movement of said spring in its biased direction, and means for positively adjusting the position of both the spring and the arm without changing their relative positions or tensions,

3. A contact structure comprising a movably mounted contact element, a supporting arm mounted adjacent said element, a flexible contact spring mounted on said arm and having a natural bias toward said element, means associated with'the arm and spring for limiting the motion of said spring toward said element, and means for simultaneously and positively adjusting the position of both said arm and said spring relative to said element without aiiecting the bias of the contact spring.

4. A contact structure comprising a movably mounted contact element, a supporting arm mounted adjacent said element, a flexible contact spring mounted on said arm and having a natural bias toward said element, means associated with the arm and spring for limiting the motion of said spring toward said element, and means for flexing said supporting arm to simultaneously and positively adjust the position of said arm and said spring relative to said element without changing the bias of said spring. 7

5. A contact structure comprising a movably mounted contact element, a supporting arm mounted adjacent said element, a flexible contact spring mounted on said arm and having a natural bias toward said element, a relatively rigid extension on said arm limiting the motion of said spring toward said element, and means, incapable of varying the bias of said contact spring, for positively and simultaneously adjusting the position of said arm and said spring relative to said element.

6. A contact structure comprising amovably mounted contact element, a supporting arm mounted adjacent said element, a flexible contact spring mounted on said arm and having a natural bias toward said element, an extension on said arm limiting the motion of said spring toward said element, and means for flexing said supporting arm to simultaneously and positively adjust the position of said arm and said spring relative to said element. 7

7. A support, a relatively rigid arm connected at one end to the support, a flexible member carried by the arm and biased to move in one direction, means for adjusting the positionof the free end of the arm and the said member without disturbing their relative positions, and means associated with the arm and member for limiting motion of the flexible member.

8. In a contact structure, a support, arelatively rigid arm connected to said support, a flexible member fixed toan intermediate part of said arm and having its free end spaced, and biased away, from said. arm, a downturned loop on the flexible member sleeving the free end of said arm, and an adjusting screw carried by said support and having its inner end bearing against said arm inwardly of the point where said arm and member are spaced apart. c

In testimony whereof I afiix my signature.

AINSLIE CARTER. 

